International law barely exists and is unenforceable. If a superpower--especially a permanent Security Council member--wants to do something, there's absolutely no recourse. Look at Russia and Crimea. That's the most egregious violation of the notion of international law in recent history, and nothing of consequence happened. The big powers can do whatever they want, and the worst response will be token economic sanctions. China is so economically intertwined with the world that nothing at all would happen unless they nuked someone.